Acoustic device



May 24, 1932- R. A. HEISING- ACOUSTIC DEVICE Filed April 50, 1923 Patented May 24, 1932 UNITED STATES RAYLIOND A. HEISING, OF MILLBURN, NEW JERSEY, ASSIGNOR-TO- WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N; Y., .A CORPORATION OF NEW YORK ACOUSTIC DEVICE Application filed April 30,

This invention relates to acoustic devices and its object is to produce an acoustic device capable of efliciently and accurately responding to and producing vibrations within the audible range.

The invention in its broadest aspect contemplates a diaphragm which is perfectly free to vibrate yet peripherally stlffened to maintain its symmetry. In the preferred form of the invention there is provided a chaphragm having a diameter somewhere in the neighborhood of of the wave length of the lowest sound to be reproduced, made of a material of such thickness and elasticity that it will efficiently transmit vibrations up to 5000 cycles. Such adiaphragm may be formed of fibrous material such as paper, and preferably shaped into a conical surface having a slope such that the stiffness of the material is largely due to flexural stiffness rather than compressional stiffness, and peripherally stiifened by turning back the edge substantially parallel with the axis of the diaphragm, or perpendicular to the elements of the cone, or by providing separate re1nforcing means and coupling with the diaphragm a suitable actuating means.

A diaphragm of the above construction supported by the vibrating means of a receiver magnet system with which it may be associated is capable of producing accurately and efiiciently all tones in the audible range and particularly those tones of low frequencies which horns are incapable of transmitting freely.

In the drawings:

Fig. 1 is a perspective view, partly broken away, of a loud speaking receiver embodying the invention; a

Fig. 2 is a detail view showing means integral with the diaphragm for reinforcing it;

Fig. 3 is a detail view of a modification wherein the reinforcing means is separate and in the form of a ring;

Fig. 4 shows an actuating device which may be used.

On a standard 5 is supported a horizontal member 6 carrying an actuating device 7. Operatively associated with the actuating device 7 by means of a vibratable rod 8 is a dia- 1923. Serial No. 635,415.

phragm 9. The diaphragm 9 is preferably made of light elastic materialsuchas paper or linen, impregnated with-phenol condensation products. Thin aluminum or duralumin or any suitable material may also be used. The size of the diaphragmdepends somewhat on the character of the sounds to be reproduced. Preferably itshould not be lessthan 9 in diameter,- a* verygood size is about 18, and-in cases where extremely low tones'are important, one 86 in diameter has been found to givevery satisfactory rcsuits. A diaphragm freeat its periphery has a lower mode of vibration than-one rigidly mounted. The lS" size 'has'been foundmost suitable for general purposes, it will reproduce very faithfully, sound vibrations from 80 to 5,000 cycles per second.

In order to maintain the symmetry of the diaphragm while vibrating, it may be reinforced by any suitable means. Preferably the edge 10 of the diaphragm is turned substantially parallel to its axis. Separate means may, however, be provided as in Fig. 3 where the reinforcing means is a ring 11 of rattan or other suitable material. The reinforcing means should be as light as is consistent with the rigidity required to maintain the symmetry of the diaphragm.

Although the invention has been illustrated in connection with the loud speaking receiver employing a magnetic system, it is obvious, that a diaphragm of this form is suitable for use in transmitting devices and also in phonograph reproducing devices.

lVhat is claimed is 1. An acoustic device comprising a conical diaphragm having a diameter approximately of the wave length of the lowest vibration to be reproduced and an annular member of circular cross-sectional area secured to portions of the diaphragm removed from the apex and vibratable therewith.

2. An acoustic device comprising a large direct acting conical diaphragm having a base diameter of not less than nine inches and an annular member secured to the peripheral portion of said diaphragm for preserving the circular symmetry thereof, and driving means attached to the apex of the diaphragm, said driving means constituting the sole support for the diaphragm and the annular member.

3. A sound-reproducing diaphragm of the free edge type, and a circumferential element attached thereto at the periphery of said diaphragm having a width small as compared to the distance to the center of the diaphragm.

1O 4. A conical diaphragm f the free edge type; and an element attached thereto at the periphery of said diaphragm having a width small as compared to the distance to the vertex of the cone.

5. A sound amplifier comprising a stand,

an arm raised from said stand, a reproducing instrumentality fixed at the end of said arm, and an amplifying diaphragm supported in a vertical plane and actuated directly by said instrumentality, said diaphragm being Wholly free and unrestrained.

\ 6. A sound amplifier comprising a stand, an arm extending from said stand, a sound reproducing device supported by said arm,

a rod supported by said sound reproducing device, and a conoidal diaphragm operatively fixed at its apex on said rod to be supported and vibrated thereby, said diaphragm being otherwise unconfined.

so In witness whereof I hereunto subscribe my name this 26th day of April, A. D. 1923.

RAYMOND A. HEISING 

